3.5 and working fine for several years now.
Used 2.5's before, no issues either.
Well, 'cept when temps get down around -10 to -30 C, then It hangs for a few restarts before it gets some heat in the drive.
This really is an isue that gets beat to death here, do a search..........
For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.
Leonardo Da Vinci